This vocabulary is too simple. You want to use somewhat advanced or intermediate English vocabulary to increase your LR score. You could refer to 20 years as 2 decades instead. One decade is 10 years so 2 decades is equal to 20 years.
As can be seen from the maps,
Do not refer to the image in your essay. Avoid doing this because you will receive deductions in the score. You should simply state what you see in the image. Remember that your reader is not capable of seeing the image at this time. So it is better for your score if you do not refer to the reader to the image.
Therefore, the school site would need more school buildings to create enough rooms for every student.
Seeing as this is a task 1 essay, you should not be making any personal observations regarding the image. You should not come to any conclusions either because this is a straightforward reporting essay. Avoid making such references so that you will not receive deductions in any section of scoring.